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H. B. ROBLKER. RETURN JMR COOLER.

No. 540,028. Patented May 28, 1895.

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H. B. ROELKER. RETURN AIR COOLER. 1

No. 540,028. Patented May .28, 41895.

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i UNTTED STATES HUGO B. ROELKEB., OF NEW YORK, N. Y.

RETURN-AIR COOLER.

SPECIFICATION forming part of Letters Patent No. 540,028, dated May 28,1895.

Application filed August 3l, 1894. Serial No. 521,796. (No model.)

Y useful Improvements in Return-Air Coolers,

of which the following is a specification.

In Letters Patent No. 484,979, granted to .me on October 25, 1892, animproved construction of a return air cooler is shown, which is used inconnection with an Allen dense-air refrigerating-machine, for whichLetters Patent of the United States were granted to Leicester Allen, No.252,921,dated January 31, 1882. This return air cooler was mainlyadapted for the larger sizes of refrigerating machines, in which largecontact-sur faces for the passage of the return-air and the utilizationof the cold still in the same are necessary. While this returnair-cooler was well adapted for the larger sizes of dense-airrefrigerating-machines, it was found in practice that for the smallersizes a simpler and cheaper construction of return-air cooler would givebetter and more satisfactory results.

JThe object of my invention, therefore, is to furnish a simple and cheapreturn-air cooler, by which the cold remainingl in the air after it hasperformed its refrigerating work is utilized for intensifying the coldof the compressed air after the same has passed through the cooler andbefore it is taken up and pushed out into the system by the expandingengine; and the invention consists of a return-air cooler, composed ofan exterior airtight shell, an interior air-tight tube provided with anumber of exterior and interior ribs or projections, forminglongitudinal passages respectively for the highly-compressed air and forthe return-air, heads at the ends of the exterior shell and interiortube, and connections formed with the exterior shell, and interior tubeand with the return-pipe, compressor, main-cooler and expanding-engine,

as will be fully described hereinafter and finally pointed out in theclaims.

In the accompanying drawings, Figure 1 represents a side elevation of myimproved return-air cooler. Fig. 2 is partly a horizontal section online 2a 2a, Fig. 1, and partlya vertical longitudinal section on line 22, Fig. 3. Fig. 3 is' an elevation of one end of the cooler,

showing its connection. Fig. 4. is a vertical transverse section of thecooler, showing the blocks and straps by which it is connected with the-main cooler; and Fig. 5 is a vertical transverse section on line 5 5,Fig. 1, showing .the interior parts of the air-cooler drawn on a largerscale. Y Y' Similar letters of reference indicate corresponding parts.

In the drawings, A represents my improved return-air cooler, which isinterposed in the usual manner between the main cooler,expanding-engine, compressor and the returnpipe of asystem ofrefrigerating-pipes, which are connected with the expanding-en gine. gIn the return-air cooler, the returning air, which is considerablycolder than the water used for cooling the air in the main air-cooler,is employed for imparting a still lower degree of temperature to the airthat has been compressed in the compressor and deprived of its heat ofcompression in the main-cooler, so that the air is conducted at a lowertemperature than heretofore to the expanding-engine and into the systemof refrigerating-pipes connected therewith.

My improved return-air cooler Aconsists more especially of an exteriorair-tight cylinder or shell a, which is closed tightly at one end by ahead a', having a connection ax. The other end is provided with a flangea2 and bolts a3, by which the shell a is fastened to the inner tube B.Theinner air-tight tube B is provided with a number of longitudinalexterior and interior ribs or projections b b', which form a series ofexterior and interior channels for the separate passage of thecompressed air on the one side and for the returnair on the other side.The end of the inner tubeB is closed by an air-tight head B', while theother end is formed into aange b2 which abuts against the flange c2 ofthe outer shell a.. The flange b2 has also formed on it anumber of necksb3, b4, b5 by which the highly compressed air and the return-air areconducted to the channels of the inner tube B, as shown in Figs. 1 and2. The contracted neck b4 of the tube B supports a'central leading tubeC, which separates the inlet and outlet necks of the inner tube B. Allthe necks are formed with flanges, by which they are connected with thepipes which lead the air IOO from the main-cooler to the return-aircooler and from it to the expanding-engine, and the pipes which lead thereturn-air through the channels formed by the ribs of the inner tube ofthe return-air cooler. The return-pipe is connected with the neck b5, sothat the return-air is passed rst through the inner longitudinalchannelsof the tube B to the tapering ends of the inner ribs b of the same, thenthrough the central tube C to the contracted neck b4 of the inner' tubeB and then back to the compressor. By its passage through the interiorchannels formed by the inner tube B, the cold still contained in thereturn-air is communicated to the surface of the outer channels of theinner tube B, through which the highly-compressed air that is passedfrom the main-cooler to the expanding-engine is conducted. As thehighly-compressed air is thus subjected to the lower temperature of thereturn-air, its temperature is still more reduced, as it passes throughthe return-air cooler to the expanding-engine whereby the cold stillcontained in the return-air is utilized in a very effective manner.

The return-air cooler Ais supported alongside of the main air cooler Dby means of Wooden blocks D and straps D2, that are bolted to the mainair-cooler, as shown in Fig. 4. Whenever it is desired to increase themetallic surface with which the passing` air is placed in contact, loosebars or strips c Which are bent into angular, circular or other suitableshape, are inserted in the channels formed by the outer and inner ribsof the tube B with the exterior shell ct and the central tube C, asshown in Fig. 5. These bars or strips act in the same manner as thestrips shown in my prior patent, No. 484,979, referred to, and furnishin connection With the -channels formed by the ribs of the inner tube,the outer shell and the central tube, a comparatively sim* ple, cheapand very effective return-air cooler for use with the refrigeratingmachines referred to.

Having thus described my invention, l

claim as new and desire to secure by Letters Patent l. In a dynamicrefrigerating apparatus, a return-air cooler, composed of an exteriorairtight shell, an interior air-tight tube provided With exteriorandinterior longitudinal ribs or projections, forming a number ofseparated channels for the highly-compressed air and the return-air,heads at the ends of the exterior shell and the interior tube, andconnections formed respectively between the exterior shell and theinterior tube, substantially as set forth.

2. In a dynamic refrigerating-apparatus, a return-air cooler, composedof an exterior airtight shell, an inner air-tight tube provided withlongitudinal exterior and interior ribs or projections, forming a numberof separated channels respectively for the highly-compressed air, andthe return-air, heads at the ends of the exterior shell and inner tube,a central tube at the inside of the inner tube, and connections formedrespectively with the exterior shell and inner tube, and With thereturn-pipe, compressor, main-cooler and expanding-engine, substantiallyas set forth.

3. In a dynamic refrigerating machine, a return --air cooler, composedof an exterior shell, an inner tube, provided With longitudinal exteriorand interior ribs or projections forming channels, a central tube Withinthe inner tube, loose bars or strips inserted into said channels, headsat the ends of the exterior shell and inner tube, and connections formedrespectively With the exterior shell and the inner tube, and withthereturn-pipe, compressor and expanding-engine of the refrigeratingmachine,substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

HUGO B. ROELKER. 1Witnesses:

S. E. SMITH, K. R. BRENNAN.

